An investigation of coupled synoptic and mesoscale environments in the development and enhancement of severe storms in North Carolina, South Carolina, and Virginia

While environments conducive to severe storm (defined as wind >58mph., or hail 0.75&inches; or greater, or a tornado) development in the Great Plains and Midwest regions of the United States are well understood, the mid-Atlantic region's proximity to the Appalachian Mountains and Atlantic Ocean creates unique severe storm environments that are difficult to identify using conventional wisdom. Therefore the purpose of this study is to identify the synoptic scale flow regimes, and thermodynamic and kinematic structure of the mid-Atlantic atmosphere responsible in the generation of severe storms. This study will also investigate the role of the Earth's heterogeneous surface in the development of severe storms.; Storm Data© is used to develop the spatial and temporal distributions of severe storms. RAOB data is used in the construction of mid-level flow patterns for storm and non-storm days. RAOB data is also used in the development of storm specific thermodynamic and kinematic diagrams. Through statistical analysis these data indicate differences in the mid-level flow patterns associated with tornadoes and hail as compared to non-storm days. Differentiation in the surface and mid-level flow patterns can also be made between tornadic and non-tornadic storms. These mid-Atlantic severe storms tend to form in an environment characterized by a deep layer of moisture and therefore stability indices, as currently interpreted, need to be modified, as they do not adequately depict the potential for severe weather, in the mid-Atlantic region. Many mid-Atlantic storms form in regions where synoptic scale instability and shear are absent, suggesting that meso or local scale influences may create environments conducive to severe storm generation. This study identified three regions in which many severe storms formed in environments absent of instability and shear near land-surface discontinuities suggesting that differential surface heating may play a role in the development of severe storms in the mid-Atlantic.